Utilizing a convection cooled electronic circuit card for producing a conduction cooled electronic card module

ABSTRACT

A conduction cooled electronic card module is designed for insertion into a chassis of an electronic device so as to transfer thereto a heat generated by electronic components of the module. The module comprises a circuit card of a convection cooled type, and a thermally conductive frame carrying the circuit card. The circuit card has a front surface carrying at least a part of the electronic components, and a rear surface at least edge areas of which are adapted to be in thermal contact with the chassis. The frame is in thermal contact with the part of the electronic components and with the front surface of the circuit card at least at edge areas thereof, so as to conduct heat generated by the electronic components, via the edge areas of the front surface to the edge areas of the rear surface of the circuit card.

FIELD OF THE INVENTION

[0001] The present invention relates generally to cooling of electronicdevices and, in particular, to cooling electronic circuit cards.

BACKGROUND OF THE INVENTION

[0002] In conventional electronic devices such as, for example, computersystems, electronic components are mounted on circuit cards, which areassembled into electronic circuit card modules. The circuit card modulesare usually inserted into a chassis of an electronic device and,typically, plugged via a connector into an enclosure having a backplaneor a motherboard. The circuit card modules may also include additionalcircuit cards, which are called mezzanine cards. The mezzanine card iselectrically connected to the main card via a connector.

[0003] There are several standards defining properties of circuit cardmodules, for instance, VMEbus, SEM-E, PCI, cPCI standards, etc. Thestandards encompass mechanical specifications such as card dimensions,connector specifications, etc, along with electronic specifications suchas bus structures, signal functions, timing, signal voltage levels, andmaster/slave configurations. These specifications enable differentmodules of the same standard supplied from different manufacturers toplug into any enclosure of the same standard, and provide forcommunications between different modules.

[0004] Proper cooling of electronic components in general, and thosemounted on circuit cards in particular, is essential in electronicdevices, wherein excessive heat generated by the electronic componentscan cause malfunctions and failure thereof. Depending on the manner ofcooling, conventional circuit cards and, consequently, circuit cardmodules, are generally classified under convection cooled and conductioncooled types. In general, in the framework of the same standard,conventional convection and conduction cooled card modules are differentin construction, however, both meeting the same standard electronicspecifications.

[0005] Convection cooled card modules are mounted within chassis of anelectronic device in such a way as to allow the free flow of cooling airover electronic components to dissipate excess heat generated. The flowof air is usually provided by fan.

[0006] One example of a conventional convection cooled card module ofVME64 standard is shown in FIG. 4 of the drawings. The card module shownin FIG. 4 comprises a circuit card A having a front surface B and a rearsurface C, at least the front surface bearing electronic components D.The card module further comprises a standard VME interface front panel Emounted to the top of the circuit card A, including extractors F,alignment pins G, and keying provisions H for the insertion of themodule in a chassis of an electronic device; and two VMEbus connectors Iand J mounted to the bottom of the circuit card A, for the connectionthereof to an enclosure that also conforms to the VME64 standard. Themain card shown in FIG. 4 also comprises a stiffening rib providedtherealong to inhibit vibration of the card in use.

[0007]FIG. 5 illustrates another example of a conventional convectioncooled card module meeting the same VME64 standard, which in addition tothe circuit card A, comprises a mezzanine card K which has electroniccomponents L.

[0008] Convection cooled card modules can typically not be used whenthere are severe requirements for protection of their cards from harshenvironment such as sand, dust, humidity, etc. They also cannot be usedin closed electronic devices where air ventilation is impossible.

[0009] Under the above conditions, conduction cooled card modules areconventionally utilized. In such modules, heat generated by electroniccomponents of a circuit card is absorbed by an internal heattransmitting layer thereof, often made of copper, and thereby forwardedto a dissipation device, being commonly called a heat sink. The functionof this device is usually fulfilled by the chassis in which the modulesare mounted. Since a conduction cooled circuit card does not require anair exchange over its electronic components, it may be hermeticallysealed within its module or rather used in a sealed electronic device,as it happens most often.

[0010] However, in conventional conduction cooled modules, the amount ofheat that may be withdrawn from electronic components is rather low(about 15-20 watt), in view of which measures are taken to ensure thatthese cards and their components can withstand high temperatures. Thisessentially increases the costs of production of conduction cooledmodules and, consequently, their price.

[0011] Various attempts have been made to improve conduction cooling inconduction cooled circuit cards by providing a plurality of special heatwithdrawing devices for their physical attachment to electroniccomponents of the conduction cooled cards. However, this requiresconnecting the devices to the dissipation device, which may needaccurate machining, is time consuming and, particularly, is not suitablefor mass production.

[0012] Accordingly, it is an object of the present invention to utilizea standard convection cooled circuit card for the production of a novelconduction cooled circuit card module.

SUMMARY OF THE INVENTION

[0013] According to one aspect of the present invention, there isprovided a conduction cooled electronic card module comprising a circuitcard of a convection cooled type of the same standard, having front andrear surfaces and two opposite edges adapted to be received in a chassisof an electronic device. At least the front surface of the circuit cardcarries electronic components, at least a part of which is capable ofgenerating heat during operation of the module. The rear surface of thecircuit card is adapted to be in thermal contact with said chassis at anarea of the surface adjacent said edges, when the module is insertedtherein. The module further includes a thermally conductive frame onwhich said circuit card is mounted, so as to be in thermal contact withat least said part of the electronic components and with an edge area ofthe front surface of the circuit card, adjacent said edges. This enablesthe heat generated by the electronic components of the circuit card tobe transferred to the frame and therefrom, via the edge areas of thefront and rear surfaces of the card, to the chassis.

[0014] Preferably, the circuit card is provided with a thermal vias atthe edge areas thereof. This facilitates the hear transfer from thefront surface of the card to its rear surface.

[0015] Preferably, the card module further comprises a first heattransfer pad made of thermally conductive material that is sandwichedbetween the circuit card and the frame. The pad is designed forenhancing the thermal contact between the frame and the electroniccomponents. Therefore, the kind of material of which its pad is made andits thickness are to be chosen so as to ensure the provision of athermal contact between the pad and the electronic components havingvarious heights. Thus, it is preferable that the pad material is a softviscoelastic material and it may even be in the form of a gel.

[0016] The card module may further comprise at least one mezzanine cardas the circuit card. The mezzanine card is attached to said frame sothat the frame is sandwiched between the main card and the mezzaninecard, the latter being electrically connected to said main card via atleast one connector arranged in said frame. The frame is thus adapted tobe in thermal contact with electronic components of the mezzanine cardto withdraw therefrom heat generated by these components. Preferably,the module further includes a second pad made of thermally conductiveelastic material, to be sandwiched between the mezzanine circuit and theframe.

[0017] Preferably, the frame has a base surface adapted to be in thermalcontact with said electronic components on the front surface of thecircuit card and at least two peripheral side walls adapted to be inthermal contact with the edge areas of the front surface of the circuitcard. Preferably, the frame has side walls all along the circumferenceof the base surface so that, if the main card does not have electroniccomponents on its rear surface, its sealing may be achieved by simpleattaching said card to the frame. When the rear surface of the circuitcard also bears heat generating electronic components, a rear covershould be attached to the frame. A front cover should be used when themezzanine card has such components on its rear surface. When the rearsurfaces of the main and mezzanine cards bear heat generating electroniccomponents, the front and rear covers may serve to transfer heatgenerated thereby to said frame.

[0018] For sealing the main card and, optionally, the mezzanine card inthe module, the latter should comprise both rear and front coversattached to said frame, with appropriate gasket sandwiched therebetween.When the module is hermetically sealed, it is protected from humidityand it may be used when there are severe requirements for protectionfrom any harsh environment.

[0019] Preferably, both the main card and the mezzanine card of themodule meet requirements of a specific standard, and said thermallyconductive frame meets corresponding requirements of mechanicalspecifications of said standard.

[0020] In accordance with another aspect of the present invention, thereis provided a method of utilizing a convection cooled circuit card forproducing a conduction cooled electronic card module.

[0021] In accordance with a still further aspect of the presentinvention, there is provided a kit comprising a convection cooledcircuit card and parts to be assembled therewith for producing aconduction cooled card module according to the present invention and aconvection cooled card module, both adapted for insertion into acorresponding chassis of an electronic device.

[0022] The present invention provides for a conduction cooled cardmodule, which is based on a convection cooled card and is, therefore,much simpler in production and cheaper than the conduction cooled cardmodules. The significance of the present invention goes beyond thepreparation of highly reliable, stable, and cost-effective conductioncooled card modules meeting standard requirements. Since the cardmodules may be sealed, the modules retain superior performance in harshenvironments. The products are better suited for applications needed forruggedization (for example, the ability to withstand shock andvibration). Additionally, the modules are better suited in systemsneeded for extended temperature operation and in life-critical andquality-sensitive applications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to understand the invention and to see how it may becarried out in practice, preferred embodiments will now be described, byway of non-limiting example only, with reference to the accompanyingdrawings, in which:

[0024]FIG. 1 is an exploded isomeric view of a conduction cooled cardmodule constructed in accordance with one embodiment of the presentinvention;

[0025]FIG. 2 is an exploded isomeric view of a conduction cooled cardmodule including a mezzanine card and constructed in accordance withanother embodiment of the present invention;

[0026]FIG. 3a is an isomeric front view of the assembled conductioncooled card module shown in FIG. 1 or FIG. 2;

[0027]FIG. 3b is an isomeric rear view of the assembled conductioncooled card module shown in FIG. 1 or FIG. 2;

[0028]FIG. 4 is an isomeric view of a conventional convection cooledmodule; and

[0029]FIG. 5 is an exploded isomeric view of another conventionalconvection cooled card module including a mezzanine card.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030]FIGS. 1 and 2 illustrate conduction cooled modules 10 and 20,respectively, which in accordance with the present invention aredesigned to meet requirements of the VMEbus standard (Versa ModuleEurocard) and are produced based on a convection cooled circuit card Aof the same VMEbus standard, shown in respective FIGS. 4 and 5. Themodules 10 and 20 are adapted for insertion into a chassis of anelectronic device (not shown), designed for conduction cooled cardmodules.

[0031] The circuit card A has front and rear surfaces B and C, at leastthe former bearing electronic components D. In order to meetspecifications of conduction cooled modules of the above of the VMEbusstandard, the rear surface C of the circuit card A is adapted forthermal contact with the chassis, at edge areas 11 and 12 of the rearsurface C. In particular, the rear surface C is provided, at the edgeareas 11 and 12, with edge guides (not seen) extending along the leftand right edges thereof.

[0032] The circuit card A is further provided with a thermal vias in theform of a plurality of thermally conductive microbores 15 formed betweenthe front and rear surfaces B and C and localized at the edge areas 11and 12 thereof to be associated with the edge guides.

[0033] The conduction cooled module 10 shown in FIG. 1, further includesa thermally conductive frame 13 mating in format with the circuit cardA. A central area (not seen) of a front surface of the frame 13, facingthe circuit card A, is adapted to be in thermal contact with theelectronic components D of the circuit card A. A peripheral area 14 ofthe front surface of the frame 13 is adapted to be in thermal contactwith the front surface B of the card in the area of the microbores 15.

[0034] The frame 13 comprises a pair of wedge locks 16 mounted on a rearsurface of the frame 13 at side edge areas thereof, and a pair ofextractors 29 mounted at an upper edge area of the rear surface of theframe 13, which are designed for facilitating the insertion/extractionof the module 10 in/from the chassis of an electronic device.

[0035] The conduction cooled module 10 further includes a heat transferpad 17 made of a thermally conductive viscoelastic material, to besandwiched between the circuit card A and the frame B so as to enhancethermal contact between the frame 13 and the electronic components Dmounted on the front surface B of the circuit card A. The kind of thepad material and its thickness are to be chosen so as to ensure theprovision of a thermal contact between the pad and the electroniccomponents having various heights. It is therefore preferable that thepad material is a soft viscoelastic material and, when the difference inheights between the electronic components D is essential, this materialmay even be in the form of a gel.

[0036] The conduction cooled module 10 further includes front and rearcovers 18 and 19, respectively, adapted to seal the circuit card Awithin the module 10. For this purpose, the module may further comprisegaskets to be sandwiched between the covers 18 and 19 and the frame 16.When the rear surface C of the card A has heat generating electricalcomponents thereon, the rear cover 19 is used also to transfer the heatgenerated by these components to the frame.

[0037] The card module 10 shown in FIG. 1 is assembled by mounting thecircuit card A to the frame 13 with the pad 17 sandwiched therebetweenso as to provide a thermal contact between the central area of the frame13 and the electrical components D mounted on the front surface C. Inaddition, a thermal contact is provided between the peripheral area 14of the front surface of the frame 13 and the front surface C of the cardA in the area of the microbores 15. The front and rear covers 18 and 19,respectively, are attached to the frame 13, optionally with the gasketssandwiched therebetween.

[0038] The conduction cooled card module 20 shown in FIG. 2, differsfrom the card module 10 shown in FIG. 1, in that, in addition to thestandard circuit card A which constitutes its main card, it comprises amezzanine card K of the same standard, which is shown in FIG. 5. Themezzanine card K is to be attached to a frame 23 so that this frame issandwiched between the main circuit card A and the mezzanine card K. Themezzanine card K, which carries electronic components L at least at itsfront surface facing the frame 23, is adapted to be electricallyconnected to the main circuit card A via a connector 24 that is arrangedin the frame 23.

[0039] The card module 20 may further comprise a heat transfer pad 25made of a thermally conductive elastic material, similar to the pad 17described above, to be sandwiched between the mezzanine card K and theframe 23 for enhancing the thermal contact between the frame 23 and theelectronic components of the mezzanine card K.

[0040] The conduction cooled model 20 further includes front and rearcovers 27 and 28, respectively, to be attached to the frame 23 forsealing the circuit card A and the mezzanine card K within the module20. In the present embodiment, the mezzanine card K carries electroniccomponents L also on its rear surface facing the front cover 27 and athermal contact is provided between the front cover 27 and theelectronic components L.

[0041]FIGS. 3a and 3 b show, respectively, front and rear views of theassembled conduction cooled card module 10 or 20. As seen, the module ishermetically sealed and it may be used when there are severerequirements for protection from any harsh environment.

[0042] When the card module 10 is in operation, the heat generated bythe electronic components D mounted on the front surface B of thecircuit card A is transferred through the first heat transfer pad 17 andthe frame 13 to the front surface B of the card A at the area of thethermal vias 15 and, therethrough, to the rear surface C of the cardwhich transfers the heat to the chassis of an electronic device. If theelectronic components are mounted also on the rear surface C of thecircuit card A, the heat generated thereby is transferred via the rearcover 19 to the frame 13 and therefrom to the rear surface C of thecircuit card A and to the chassis.

[0043] The card module 20 operates similarly to the card module 10. Inaddition, heat generated by the electronic elements L of the mezzaninecard K is transferred to the frame 23 via the second heat transfer pad25, and then to the rear surface 14 of the main circuit card A.

[0044] It should be appreciated that the present invention enablesutilizing a standard convection cooled circuit card used for producing astandard convection cooled module, in the production of a conductioncooled module meeting all standard requirements. Consequently, such acircuit card, together with parts of these modules that are necessaryfor their assembling, may be combined in a kit. Various configurationsof such kits are possible according to the invention. For example, in amost complete configuration, the kit may comprise the circuit card A,the mezzanine card K, a frame, first and second pads, front and rearcovers and two gaskets, for the assembly of conduction cooled cardmodules such as 10 in FIG. 1 or 20 in FIG. 2; and an interface frontpanel E with all appropriate appliances for the assembly of convectioncooled card modules such as shown in FIG. 4 or FIG. 5.

[0045] As it should be understood by a man of the art, the invention isnot confined to the precise details of the foregoing examples andvariations may be made thereto. Hence, the circuit cards of VMEbusstandard used in the description of the preferred embodiment were usedas a non-limiting example of implementation of the present invention.The present invention should not be considered as being limited to theuse of any particular standard. A similar solution can be implemented onthe circuit cards of any other conventional design or appropriatestandard, for example, SEM-E, PCI or cPCI circuit card standards andtheir modifications. It may also be designed in a non-standard format.

[0046] Also, it should be clear to a versed man that, though the thermalvias providing a convection heat transfer between the front and rearsurfaces of the circuit card A, are desirable for improving the heattransfer between these surfaces, they can be omitted. Alternatively,they may be converted into thermal conductive channels by filling themicrobores with a conductive material. Further, the module may bedesigned without the heat transfer pad or rather this pad need not be ofelastic only, but may be of metal, for example, aluminium, copper, oranother good thermal conductor.

[0047] Also, the frame may be not only in the form of a continues solidbody, but it may be of hollow design. In accordance with the laterdesign, the frame can be cooled by passing therethrough an air or acoolant fluid.

[0048] Other variations are possible within the scope of the presentinvention as defined in the appended claims.

List of References Used in the Drawings

[0049] A—convection cooled circuit card

[0050] B—front surface of the circuit card A

[0051] C—rear surface of the circuit card A

[0052] D—electronic components

[0053] E—interface front panel

[0054] F—extractors

[0055] G—alignment pins

[0056] H—keying provisions

[0057] I, J—connectors

[0058] K—mezzanine card

[0059] L—electronic components of the mezzanine card K

[0060]10—conduction cooled module in FIG. 1

[0061]11,12—edge areas of the rear surface C

[0062]13—thermally conductive frame of the module 10

[0063]14—peripheral area of the surface of the frame 13

[0064]15—microbores

[0065]16—wedge locks of the frame 13

[0066]17—heat transfer pad of the module 10

[0067]18, 19—front and rear covers of the module 10

[0068]20—conduction cooled module in FIG. 2

[0069]23—thermally conductive frame of the module 20

[0070]24—connector of the module 20

[0071]25—heat transfer pad of the module 20

[0072]27, 28—front and rear covers of the module 20

[0073]29—extractors of the frame 13

1. A conduction cooled electronic card module comprising: a thermallyconductive frame; and a circuit card having a front surface carrying atleast a part of a plurality of electronic components, a rear surface,and top, bottom and side edges; said circuit card being assembled withsaid frame so that said front surface of the frame is in thermal contactwith said part of the electronic components and with said front surfaceof the circuit card at least at edge areas thereof adjacent said sideedges, and so as enable the insertion of the module, by means of saidframe, into a conduction fooled module chassis of an electronic deviceto transfer thereto, via said frame, heat generated by electroniccomponents of the module; wherein said circuit card is of a convectioncooled type and has front panel mounting holes formed adjacent the topedge of the card for mounting thereon a front panel, when the card isused without said frame, to form a conduction cooled module adapted forinsertion in a convection cooled module chassis by means of said frontpanel.
 2. A module according to claim 1, wherein said frame is metallic.3. A module according to claim 1, wherein said circuit card is formedwith thermal vias extending between the front and rear surfaces of thecard at said edge areas thereof.
 4. A conduction cooled module asdefined in claim 3, wherein said thermal vias are microbores adapted forproviding a convection heat transfer from the front surface of the saidcircuit card to said edge area of the rear surface of said circuit card.5. A module according to claim 1, further comprising a first heattransfer pad made of a thermally conductive material sandwiched betweensaid circuit card and said frame, for enhancing the thermal contactbetween the frame and at least said part of the electronic components.6. A module according to claim 5, wherein said material is viscoelasticand is adapted for providing said thermal contact with the electroniccomponents having various heights.
 7. A module according to claim 1,wherein said circuit card is a main card of the module whichadditionally comprises at least on mezzanine card carrying electroniccomponents at least on its front surface, and attached to said frame sothat the frame is sandwiched between the main card and the front surfaceof the mezzanine card, the latter being electrically connected to saidmain card via at least one connector arranged in said frame.
 8. A moduleaccording to claim 7, further comprising a second heat transfer pad madeof a thermally conductive material and sandwiched between said mezzaninecircuit card and said frame, for enhancing the thermal contacttherebetween.
 9. A module according to claim 8, wherein said material isviscoelastic and is adapted for providing said thermal contact with theelectronic components having various heights.
 10. A module according toclaim 7, wherein said frame further comprises a slit for said connector.11. A module according to claim 1, further comprising front and rearcovers attached to said frame, for sealing the module with said circuitcard therein.
 12. A module according to claim 7, further comprisingfront and rear covers attached to said frame, for sealing the modulewith said main card and mezzanine card therein.
 13. A module accordingto claim 7, wherein the main card and the mezzanine card of the modulemeet requirements of a specific standard, and said thermally conductiveframe meets requirements of mechanical specifications of said standarddefined for card modules.
 14. A conduction cooled module as defined inclaim 1, wherein said specific standard is one of the VMEbus and SEM-E,PCI and cPCI circuit card standards or their modifications.
 15. A methodof producing a conduction cooled electronic card module, comprisingproviding a circuit card of a convection cooled type having front andrear surfaces with top, bottom and side edge areas, and carrying heatgenerating electronic components at least at its front surface, said topedge area of said convection cooled circuit card being formed with frontpanel mounting holes designed for mounting on said top edge a frontpanel to form a conduction cooled module adapted for insertion in aconvection cooled module chassis by means of said front panel; providinga thermally conductive frame and assembling said frame with said card,when the card is free of said front panel, so as to provide a thermalcontact between said frame and said electrical components mounted on thefront surface, and a thermal contact between the frame and said sideedge areas of the circuit card, and so as to enable the insertion of themodule, by means of said frame, into a conduction cooled module chassisof an electronic device to transfer to said chassis, via said frame,heat generated by electronic components of the module.
 16. A methodaccording to claim 15, further comprising a step of providing thermalvias extending between the front surface of the card and said edge areasof its rear surface adapted to be in thermal contact with said chasses.17. A method as defined in claim 16, wherein said thermal vias are inthe form of microbores adapted for providing a convection heat transferfrom the front surface of said circuit card to said edge areas of therear surface of said circuit card.
 18. A method according to claim 16,further comprising a step of providing thermally conductive guides andmounting them at said edge areas of the rear surface of the circuitcard.
 19. A method according to claim 15, further comprising the stepsof: providing a first heat transfer pad made of a thermally conductivematerial; and sandwiching said pad between the front surface of saidcircuit card and said frame, wherein enhancement of the thermal contactbetween the frame and the electronic components of said front surface isprovided.
 20. A method as defined in claim 15, wherein said circuit cardconstitutes a main card of the module, the method further comprising thesteps of: providing a mezzanine circuit card carrying electroniccomponents at least on its front surface; mounting the mezzanine circuitcard to said frame so as to provide a thermal contact between theelectronic components of said front surface of the mezzanine card andthe frame; providing a connector for connecting said mezzanine card withsaid main circuit card; mounting said connector on said frame; andproviding an electrical connection between the main circuit card and themezzanine card via said connector.
 21. A method according to claim 20,further comprising the steps of: providing a second heat transfer padmade of a thermally conductive material; and sandwiching said second padbetween the electronic components of said front surface of the mezzaninecard and said frame.
 22. A method as defined in claim 15, furthercomprising the steps of: providing front and rear covers; and attachingsaid covers to said frame for sealing the module with said circuit cardtherein.
 23. A method as defined in claim 20, further comprising thesteps of: providing front and rear covers; and attaching said covers tosaid frame for sealing the module with said main card and mezzanine cardtherein.
 24. A kit for assembling conduction cooled and convectioncooled electronic card modules comprising: a circuit card of aconvection cooled type having front and rear surfaces with top, bottomand side edge areas, and carrying heat generating electronic componentsat least at its front surface, said top edge area of said convectioncooled circuit card being formed with front panel mounting holesdesigned for mounting on said top edge a front panel for the insertionof said card in a convection cooled module chassis; a thermallyconductive frame for assembling said frame with said circuit card, toform a conduction cooled electronic card module as defined in claim 1;and said front panel adapted for being mounted to said circuit card bymeans of said mounting holes, to form a convection cooled module.
 25. Amethod of producing a convection cooled circuit card and a conductioncooled card module by utilizing a kit according to claim
 24. 26. A kitaccording to claim 24, wherein the convection cooled circuit card isconfigured to meet requirements of a specific standard defined for cardmodules.
 27. A conduction cooled electronic card module comprising: acircuit card of a convection cooled type having a front surface carryingat least a part of some electronic components, a rear surface and edgeareas free of said components; a thermally conductive frame assembledwith said circuit card; a first heat transfer pad made of a thermallyconductive material sandwiched between said circuit card and said frameand being in direct contact with said part of the electronic components,for enhancing the thermal contact between the frame and at least saidpart of the electronic components; wherein said frame is adapted forconducting heat generated by said electronic components, to the edgeareas of the circuit card, and wherein said module is adapted for theinsertion in a chassis designed for conduction cooled card modules, bymeans of said frame, so that said edge areas of the circuit card arereceived in said chassis in thermal contact therewith to transfer to thechassis a heat generated by electronic components of the module.
 28. Amodule according to claim 27, wherein said material is viscoelastic andis adapted for providing said thermal contact with the electroniccomponents having various heights.
 29. A module according to claim 28,wherein said circuit card is a main card of the module whichadditionally comprises at least one mezzanine card carrying electroniccomponents at least on its front surface, and attached to said frame sothat the frame is sandwiched between the main card and the front surfaceof the mezzanine card, the latter being electrically connected to saidmain card via at least one connector arranged in said frame.
 30. Amodule according to claim 29, further comprising a second heat transferpad made of a thermally conductive material and sandwiched between saidmezzanine circuit card and said frame, for enhancing the thermal contacttherebetween.
 31. A module according to claim 30, wherein said materialis viscoelastic and is adapted for providing said thermal contact withthe electronic components having various heights.
 32. A method ofutilizing a convection cooled circuit card designed for insertion in aconvection cooled card module chassis of an electronic device, forproducing a conduction cooled electronic card module adapted for theinsertion thereof into a chassis of an electronic device designed forconduction cooled card modules, the circuit card having front and rearsurfaces with edge areas and carrying heat generating electroniccomponents at least at its front surface, the method comprising thesteps of: providing a thermally conductive frame for bearing saidcircuit card; providing a first heat transfer pad made of a thermallyconductive material; assembling said card with said frame with said padsandwiched between the front surface of said circuit card and said frameso as to provide a direct contact between said pad and said electricalcomponents mounted on the front surface, and to provide a thermalcontact between the frame and the edge areas of the circuit card,wherein the frame is adapted for conducting heat generated by saidelectronic components to said edge areas of the circuit card, andwherein said module is adapted for the insertion in said chassisdesigned for conduction cooled card modules, by means of said frame, sothat said edge areas of the circuit card are received in said chassis inthermal contact therewith to transfer to the chassis a heat generated byelectronic components of the module.
 33. A method as defined in claim32, wherein said circuit card constitutes a main card of the module, themethod further comprising the steps of: providing a mezzanine circuitcard carrying electronic components at least on its front surface;mounting the mezzanine circuit card to said frame so as to provide athermal contact between the electronic components of said front surfaceof the mezzanine card and the frame; providing a connector forconnecting said mezzanine card with said main circuit card; mountingsaid connector on said frame; and providing an electrical connectionbetween the main circuit card and the mezzanine card via said connector.34. A method according to claim 33, further comprising the steps of:providing a second heat transfer pad made of a thermally conductivematerial; and sandwiching said second pad between the electroniccomponents of said front surface of the mezzanine card and said frame.